The invention related to a holding and adjusting apparatus for a rotating magnetic head arrangement. A two-channel magnetic tape recorder for recording and/or playing back digitally encoded video signals is already known from EP-OS 158 373, in which a magnetic tape is coiled around a scanning device at an angle of approximately 180.degree. and which therefore comprises two pairs of recording and playback magnetic heads which are located diametrically opposite one another. In order for the magnetic heads to precisely follow the previously recorded tracks on the magnetic tape during playback, each pair of these magnetic heads, which are located closely adjacent to one another, is arranged on a piezoelectric deflecting element which enables a displacement of this magnetic head pair transversely relative to the track direction on the basis of corresponding track following signals. The recorded track picture of the magnetically readable tracks on the magnetic tape must generally correspond to the established standard with very close tolerances so as to ensure the exchange of magnetic tapes between devices of the same type. The relative position of the two magnetic heads of a magnetic head pair relative to one another must therefore be adjustable within very close tolerances.
An embodiment of such a holding device for two magnetic heads which are arranged closely adjacent to one another is disclosed in EP-OS 144 719. However, this involves a recording and playback magnetic head and an adjacent erasing head. This publication also does not show how the relative position of the two magnetic heads relative to one another can be adjusted with existing manufacturing tolerances.
Therefore, in a track following device of a magnetic recording and playback device, according to the EP-OS 54 419, the four magnetic heads, which are arranged in a row for parallel recording of digitally encoded video signals, are arranged on a slotted block at the tip of a piezoelectric deflecting device, wherein the height adjustment of the magnetic heads relative to one another enables a division into individual block parts. In this construction, however, the distance of the magnetic heads from one another must already lie within the allowable tolerances and cannot be changed subsequently. Moreover, the height adjustment within the required close tolerance areas is difficult to effect because of the resilient material characteristics.
A similar suggestion for changing the relative position of two adjacent magnetic heads on a rotating head wheel is disclosed in DE-OS 31 21 791. The arrangement of each magnetic head on a spring small metal plate makes it possible, in conjunction with adjusting screws provided transversely relative to a bending direction, to adjust the height of the magnetic heads relative to one another and to a reference plane, but no auxiliary means is provided for the likewise difficult angle adjustment and the adjustment of the spacing (distance) relative to one another.
An adjusting device for two magnetic heads, which are arranged diametrically at the circumference of a revolving head disk, is already known from the U.S Pat. No. 3,679,838. The adjusting device permits height and circumferential adjustment of each magnetic head by expanding elements and pressure screws. In addition, DE-AS 2361802 discloses an adjusting device for a magnetic head which is displaceable on a carriage along a chord of the head wheel disk. However, the known apparatus serves to adjust the end projection of the head mirror over the radius of the revolving head disk.
Moreover, U.S. Pat. 4,117,522 discloses a precision adjusting apparatus for adjusting the height of a magnetic head, its angular position in the radial direction, and its angular position in the circumferential direction. However, the position of the magnetic head in the circumferential direction, i.e. the distance from the rest of the additional magnetic heads arranged at the circumference of the head wheel, cannot be adjusted.
Finally, a converter holding device for a tape recording and/or playback device is known from the DE-OS 31 14 453, which enables an adjustment of every converter arranged at the circumference of a head disk in radial and circumferential directions. For this purpose, every transducer is fastened on a carrier which can be displaced in two directions by a plurality of screws bevel heads which engage the carrier at various places. An angular adjustment of the converter gap in the azimuth direction is not possible.
All of the holding and adjusting devices known to the Applicant herein have in common the fact that they either enable an adjustment in only two of three possible axial directions or require so much space that their application to closely located magnetic heads is not possible.